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A Case of Acute Bilateral Solar Retinopathy Diagnosed with Spectral Domain Optical Coherence Tomography
摘要： To report a case of acute bilateral solar retinopathy diagnosed using spectral domain optical coherence tomography (SD-OCT). Case summary: A 74-year-old female patient consulted for amblyopia and metamorphopsia at a local hospital. On the patient’s first visit, there were no abnormal findings based on slit lamp microscope. Additional examinations were conducted since the patient complained of metamorphopsia with visual acuity and corrected vision. Fundus photography and SD-OCT examination showed symmetrical lesions near the bilateral macula. Several evaluations of the patient’s medical history confirmed that the patient was exposed directly to the sun for 30 minutes. One month after the first visit, visual acuity improved but metamorphopsia remained unchanged. Lesion status could not be confirmed by fundus photography. There was no abnormal finding on fluorescence angiography. SD-OCT examination still showed bilateral symmetric disruption of the outer retina but with no significant interval change. Conclusions: In the present case, the patient with bilateral intraocular lenses who complained of acute binocular amblyopia was diagnosed accurately through SD-OCT tests for bilateral symmetric disruption on the outer retina and repetitive evaluations of patient’s medical history.
关键词： Spectral domain optical coherence tomography (SD-OCT),Acute bilateral solar retinopathy,Patient’s medical history,Disruption
更新于2025-09-04 15:30:14
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Quantitative Evaluation of Broadband Photoacoustic Spectroscopy in the Infrared with an Optical Parametric Oscillator
摘要： We evaluate the spectral resolution and the detection thresholds achievable for a photoacoustic spectroscopy (PAS) system in the broadband infrared wavelength region 3270 nm to 3530 nm driven by a continuous wave optical parametric oscillator (OPO) with P ≈ 1.26 W. The absorption spectra, IPAS(λi), for diluted propane, ethane and methane test gases at low concentrations (c ～ 100 ppm) were measured for ～1350 discrete wavelengths λi. The IPAS(λi) spectra were then compared to the high resolution cross section data, σFTIR, obtained by Fourier Transform Infrared Spectroscopy published in the HITRAN database. Deviations of 7.1(6)% for propane, 8.7(11)% for ethane and 15.0(14)% for methane with regard to the average uncertainty between IPAS(λi) and the expected reference values based on σFTIR were recorded. The characteristic absorption wavelengths λres can be resolved with an average resolution of δλres ～ 0.08 nm. Detection limits range between 7.1 ppb (ethane) to 13.6 ppb (methane). In an additional step, EUREQA, an artificial intelligence (AI) program, was successfully applied to deconvolute simulated PAS spectra of mixed gas samples at low limits of detection. The results justify a further development of PAS technology to support e.g., biomedical research.
关键词： photoacoustic spectroscopy,optical-parametric oscillator,PAS,gas sampling,hydrocarbons,spectral deconvolution,EUREQA,OPO
更新于2025-09-04 15:30:14
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Comparison of MultiColor fundus imaging and colour fundus photography in the evaluation of epiretinal membrane
摘要： Purpose: To compare MultiColor fundus imaging (MC) and colour fundus photography (CFP) for the evaluation of epiretinal membrane (ERM). Methods: In this retrospective study, 192 eyes (181 patients) that underwent vitrectomy for ERM were imaged using Spectralis optical coherence tomography (for MC) and AFC-210 digital camera (for CFP) 1 week before vitrectomy. Two investigators independently determined the rate of delineability and ERM area for each modality. Results: The intergrader agreement rates for delineability were very high for both image modalities. The rate of delineability of ERM (%) was higher for MC than for CFP, for both investigators [70.8% versus 52.6% and 73.4% versus 53.6% (both p –)]. Epiretinal membrane (ERM) area measurement showed high agreement between investigators for MC (p = 0.466) but di?ered signi?cantly between the investigators for CFP (p –). The ERM area determined on MC was signi?cantly wider than that on CFP for both investigators (p – for investigator 1 and p – for investigator 2). Conclusion: The ERM area is more clearly detectable and widely demarcated in MC than in CFP images. MultiColor imaging (MC) may be more sensitive and accurate for early detection of ERM and ERM area measurement.
关键词： MultiColor imaging,spectral-domain optical coherent tomography,epiretinal membrane,colour fundus photography
更新于2025-09-04 15:30:14
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[ACM Press the 2018 International Conference - Hong Kong, Hong Kong (2018.02.24-2018.02.26)] Proceedings of the 2018 International Conference on Image and Graphics Processing - ICIGP 2018 - Image Change Detection Using Comprehensive Preprocessing and Spectral Log-Demons Algorithm
摘要： This paper proposes a universal framework for image change detection for daily basic use. Overall, the challenge lies on the interference factors such as noise captured during shooting, illumination variation in time-series images and rotation angle of the view. To overcome these problems, we introduce the Comprehensive Preprocessing and Spectral Log-Demons Algorithm (CPP-SLD). We begin our methodology with Comprehensive Preprocessing methods, aiming to eliminate the irrelevant factors. We analyze the sparseness property of gradient distribution to correct the bias. In addition, we make use of the symmetric distribution of the radial gradient to correct the vignetting. Besides, Wiener filtering and Gaussian filtering are both used to denoise and smooth the images. Finally, the Spectral Log-Demons algorithm is applied to register. Then by subtraction we detect the change. Our framework can achieve a widespread success under different circumstances. Moreover, we compare our method with 3 ohthers, and by qualitative and quantitative analysis we expound the validity and robustness of our method.
关键词： comprehensive preprocessing,Spectral Log-Demons Algorithm,correction,Image change detection,filter.
更新于2025-09-04 15:30:14
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A spectral domain approach for the calculation of the scattering of the stratified uniaxial electric anisotropic media under point source excitation with arbitrary orientation
摘要： A method for the calculation of the scattering of the strati?ed uniaxial electric anisotropic media (UEAM) under point source excitation with arbitrary orientation is presented. In this method, the total ?eld is decomposed into three parts, the radiated ?eld of the point source in free space, the re?ected ?eld from the top interface of the UEAM and the transmitted ?eld after multiple re?ections in the anisotropic layer. The three parts are derived in spectral domain respectively and can be expressed by using Fourier transform. Then the saddle point technique (SPT) is introduced to obtain an asymptotic solution of the scattered ?eld. Results from the asymptotic solution are compared with the results calculated by the method of moments (MOM) and the comparison shows good agreement.
关键词： uniaxial electric anisotropic,scattering,spectral domain method,Point source,saddle point technique
更新于2025-09-04 15:30:14
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Detection of gallbladder stones by dual-energy spectral computed tomography imaging
摘要： AIM: To evaluate the detectability of gallbladder stones by dual-energy spectral computed tomography (CT) imaging. METHODS: Totally 217 patients with surgically confirmed gallbladder stones were retrospectively analyzed who underwent single-source dual-energy CT scanning from August 2011 to December 2013. Polychromatic images were acquired. And post-processing software was used to reconstruct monochromatic (40 keV and 140 keV) images, and calcium-lipid pair-wise base substance was selected to acquire calcium base images and lipid base images. The above 5 groups of images were evaluated by two radiologists separately with 10-year experience in CT image reading. In the 5 groups of images, the cases in the positive group and negative group were counted and then the detection rate was calculated. The inter-observer agreement on the scoring results was analyzed by Kappa test, and the scoring results were analyzed by Wilcoxon test, with P < 0.05 indicating that the difference was statistically significant. The stone detection results of the 5 groups of images were analyzed by χ2 test. RESULTS: There was good inter-observer agreement (k = 0.772). In 217 patients with gallbladder stones, there was a statistically significant difference in stone visualization between spectral images (40 keV, 140 keV, calcium base and lipid base images) and polychromatic images (P < 0.05). 40 keV monochromatic images were better than 140 keV monochromatic images (4.90 ± 0.35 vs 4.53 ± 1.15, P < 0.05), and calcium base images were superior to lipid base images (4.91 ± 0.43 vs 4.77 ± 0.63, P < 0.05), but there was no statistically significant difference between 40 keV monochromatic images and calcium base images (4.90 ± 0.35 vs 4.91 ± 0.43, P > 0.05). In 217 gallbladder stone patients, there were 21, 3, 28, 5 and 12 negative stone cases in polychromatic images, 40 keV images, 140 keV images, calcium base images and lipid base images, respectively, and the differences among the five groups were statistically significant (P < 0.05). CONCLUSION: Monochromatic images and base substance images have a good clinical prospect in the iso-density stone detection.
关键词： Gallbladder stone,Spectral imaging,Computed tomography
更新于2025-09-04 15:30:14